Krstic is not Amare.

He may return even stronger than Amare, or much weaker than he was before.

I personally had a torn ACL 8 months ago, so you can trust me on my word it's not that easy to return 100%. Sure, he gets the ebst treatment in the world, but you have to take into consideration that basketball is the sport which destroys most knees.
Boone didn't have ONE good game. He had 2 or 3 which stood out. BUT check his numbers from the point he was inserted into the starting lineup. Oh my god, what an improvement. He just needed PT. Kidd-product maybe? Who cares if he's switching Kidd for Nash?

Darko had 4 years in this league, he was one of the biggest busts EVER. He was taken before Carmelo, Bosh, Wade. Doesn't get much worse there.
He's at the MLE, which is still overpaying him. Memphis has a fast paced offense and Darko obviously doesn't fit there. Why would he in PHX?